Bent tube boiler



June 16, 1931. J, MARSHALL 1 810565 BENT TUBE BOILER Filed A ril 4. 1929 W7- ATTORNEYS Patented June 16, 1931 E DELAWARE.

{PA'IZENT OFFICE LEONARD J. MARSHALL, OF WESTWOOD, NE JERSEY, AssIeNon- To INTERNATTONAL' COMBUSTION ENGINEERING CORPORATION, OE NEW YORK, NY, a coEronA'rmN BENT TUBE BOILE Applicatiomfiled April 4,1929; Serial No. 352,369.

This invention relates to bent tube boilers such, for example, as Stirling boilers having mud and upper steam, and water drums connected by banks of boiler tubes One of the primary objects of the invention is the provision of a boiler of the above type in. which a maximum difference in gas temperature between the riser and downcomer banks is obtained.

Another object of'the invention is the provision of improvements in the arrangement of the banks of tubes, the baffles and the steam heater location in boilers of the type above mentioned. 7

How the foregoing, together with such other objects as may hereinafter appear, or are incident to my invention, are realized, is illustrated in the accompanying drawing, wherein The figure is a more or less diagrammatic sectional elevation of a boiler. constructed in accordance with my invention. a

The boiler illustrated is of the inclined type and comprises, in generaha mud drum 2, an upper front steam and water drum 3, a second steam and water drum 4.- anda plurality of banks of tubes connecting the drums, in this instance three banks a, b and 0 being shown. A plurality of water circulators 5 and a plurality of steam circulators 6 are provided between the upper. steam and water drums 3 and 4.

The front bank a comp-rises a plurality of rows of tubes connecting the mud drum '2 withthe front steam and water drum 3, the tubes of the rows being bent away from the drums at their upper and lower portions, and the .major portion of their length being straight; The second .bank I) comprises a plurality of rows of tubes certain of which connect the mud drum with the front steam andwater drum 3'and others of which con.- nect the mud drum 2 with the second steam and water drum 4. In this instance I have shown the tubes of three of the rows'ofthis second bank connecting into the front steam and water drum 3 and the remaining six rows are shown connected into the second steam and water drum ,4. The rear bank 0 comprises a plurality of rows of tubes connecting the mud drum 2 with the second steam and water drum.

In connection with the three rows of tubes "of the second bank I) which connect into the upper drum 3,.it will be noted that they are slightly bent at their lower portions and from thence extend straight for the greater portion of their length and then bendtoward the upper i drum 3 for connection therein'to. 'The amount ofbend in the tubes of the rows'just mentioned and in the tubes of th'e'first bank is such as will provide a substantialspace Abetween the front bank a and the secondabank b, the space, vertically considered, being approximately in the shape of a. rectangle, the

long dimension'of which is in a vertical di- I.

rection. I y

In the'spacethus provided Ilocate a steam heater, such as a reheater, superheaten'or the like, which, by virtue of the rectangular shape of the space, maybe of considerable size beelements may extend for the maj or part of the length of the tube banks.

" A baflie 7 is associated with the front bank of tubes a, a baflie8 is associated with the second bankband a bafiie 9 is associated with I the rear banktubes c. The bafiie 7 is located toward the rear of the. front bank a, and, as

front upper'drum 3," thus providing a passage 10 above the baffle through which gases pass from the front bank to the space A because, with such. a space, the'steam' heater.

tween the first and second banks" The baflie 8 is "located toward the front of the second 'bank' of tubes 5, andeasxhere shown extends downwardly from the second upper drum 4 to a point short of the mud drum 2,. thus providingapassage 11 below the bafllefor the passageof gases from the space A to the, sec- 7 ond bank of tubes. In this instance the bafile then pass through the passage 11 to the sec ond bank and upwardly over the tubes therebafile for the front bank terminating short of the front steam and water drum, and a front bafile for the second bank terminating short of the mud drum and shielding all of the tubes of said second bank.

In testimony whereof I have hereunto signed my name.

LEONARD J. MARSHALL.

of to the passage 12, and finally pass downwardly over the tubes of the rear bank 0.

Through the arrangement thus described it will be seen that there is a maximum difference in the temperature of the gases to which the riser or front bank tubes are subjected and the gases to which the downcomer tubes of the second bank leading from the drum 3 to the drum 2, are subjected, which secures effective circulation.

It is to be understood that if a reheater is located in the space A, as indicated in the drawing, then a superheater may be located at some other suitable point in the installation. An alternative arrangement would be one in which a superheater is located in the space A with a reheater located at some suitable point in theinstallation.

My invention is particularly useful in a high pressure installation having multi-stage turbines, for example one in which the furnace is provided with boiler tubes defining combustion space and in which a radiant type primary superheater for the high pres sure steam is provided in the furnace and a convection type reheater for the low pressure steam' islocated in a cooler zone as shown in the drawing. By employing a convection type reheater located in the pass of the boiler between the first and second banks oftubes, the reheat temperature will not increase with decreased. capacity and the reheater will not at any time be exposed to a sufficiently high temperature to damage the elements. Owing t o'the high pressure, the greater density and specific heat of the steam will afford ample protection of the radiant superheater elements at times of decreasec capacity.

I claim I In combination, a bent tube boiler having a mud drum, upper steam and water drums and banks of tubes connecting said drums including a front bank, the tubes of which connect the mud drum and the front steam and Water drum, and a second bank certain of the tubes of which connect the mud drum and a second steam and water drum and other tubes of which connect the mud drum and the front steam and water drum, said banks of tubes being so bent as to provide a substantial space therebetween for the major part of the longitudinal extent of the banks of tubes, a steam heater in said space, a rear 

